Mark Martin on Freshwater DipsMark Martin is the Director of Marine Ornamental Research at Blue Zoo Aquatics

Angelfishes, including dwarf angelfishes from the genus Centropyge, are very susceptible to copper poisoning, which can make it difficult to treat parasitic infestations such as crypto (aka “marine ich”). For this week’s “Ask Mark” column, I am going to briefly touch on copper alternatives to treating angelfishes for a wide range of infestations.

Of course it is essential to quarantine all angelfishes (all fishes for that matter), but if, during quarantine, you discover a parasitic infestation, repeated dips and hyposalinity can be the best form of treatment. A dip can cause parasites to drop of the fish, and it can be a means for administering various medications. Dips can be used both therapeutically and as a preventative measure.

While special dipping containers can be purchased, a clean, small bucket works fine. In most cases you will begin with water from the tank into which the fish will be placed after the dip. Be sure that the temperature is about the same in both the dip and the tank from which the fish is coming. It is essential to watch the fish throughout the entire dipping process. If the fish begins to thrash or show signs of extreme distress, remove it from the dip at once.

In my opionion, the best dipping agents for the home aquarist dealing with a crypto outbreak in angelfishes are freshwater and Methylene Blue. Dipping an infested or infected angelfish in a freshwater and Methylene Blue dip is highly effective when it comes to removing external parasites and even dealing with infectious diseases.

Here’s what to do: 1) Place the infested fish in a hyposaline quarantine tank for a minimum of 28 days. 2) Perform repeated dips in freshwater (same pH and temperature as fish’s water) dosed with Methylene Blue (follow instructions on bottle for dosing amounts). 3) Regularly change the quarantine tank’s water during the treatment period.

The dip should last no longer than five minutes and should be shortened if the fish shows obvious distress. As mentioned above, the dip water pH should be the same as the quarantine tank, which will require the use of a buffer (e.g., baking soda). Finally, never dip an infested fish in freshwater if open wounds are present.